By including the EFT parametrisation of new physics effects into the predictions for
Higgs-boson pair production, new uncertainties arise, related to the truncation
of the EFT expansion, which relies on an assessment of the relevance of operator contributions to the Lagrangian in a certain well-defined counting scheme.
Furthermore, at amplitude squared level, there are several possibilities to
truncate the expansion in the canonical dimension, related to the inclusion of
squared dimension six terms and double operator insertions.
The discussion of truncation uncertainties recently gained
considerable attention in the literature [1]}, [2]}, [3]}, [4]}, [5]}, [6]}, [7]}, [8]},
showing that the uncertainties have to be assessed on a case-by-case basis.
